{{Warning|This will irrevocably destroy all data on {{ic|/dev/sdx}}.}}

+

{{Warning|This will irrevocably destroy all data on {{ic|/dev/sd'''x'''}}.}}

−

{{Note|This method does not work with UEFI boot.}}

+

{{Warning|This method does not work with UEFI boot.}}

−

{{Note|Check with {{ic|lsblk}} that the USB device is '''not''' mounted, and use {{ic|/dev/sdx}} instead of {{ic|/dev/sdx1}}. '''These are very common mistakes!'''}}

+

{{Tip|Check with {{ic|lsblk}} that the USB device is '''not''' mounted (i.e. listed but has no mountpoint), and use {{ic|/dev/sd'''x'''}} instead of {{ic|/dev/sd'''x1'''}}.

−

+

'''These are very common mistakes!'''}}

−

# dd bs=4M if=/path/to/archlinux.iso of=/dev/sdx

−

−

{{Note|Some older firmware does not understand the isohybrid hack where start of fake partition offset is 0. See https://bugs.archlinux.org/task/32189 for a fix involving isohybrid.pl.}}

+

# dd bs=4M if=/path/to/archlinux.iso of=/dev/sd'''x''' && sync

==== How to restore the USB drive ====

==== How to restore the USB drive ====

Line 41:

Line 40:

After you install Arch Linux and you're done with the USB drive, you should zero out its first 512 bytes ''(meaning the boot code from the MBR and the non-standard partition table)'' if you want to restore it to full capacity:

After you install Arch Linux and you're done with the USB drive, you should zero out its first 512 bytes ''(meaning the boot code from the MBR and the non-standard partition table)'' if you want to restore it to full capacity:

−

# dd count=1 bs=512 if=/dev/zero of=/dev/sdx

+

# dd count=1 bs=512 if=/dev/zero of=/dev/sd'''x''' && sync

Then create a new partition table (e.g. "msdos") and filesystem (e.g. EXT4, FAT32) using {{Pkg|gparted}}, or from a terminal:

Then create a new partition table (e.g. "msdos") and filesystem (e.g. EXT4, FAT32) using {{Pkg|gparted}}, or from a terminal:

Line 47:

Line 46:

* For EXT2/3/4 (adjust accordingly), it would be:

* For EXT2/3/4 (adjust accordingly), it would be:

−

: {{bc|<nowiki>

+

# cfdisk /dev/sd'''x'''

−

# cfdisk /dev/sdx

+

# mkfs.ext4 /dev/sd'''x1'''

−

# mkfs.ext4 /dev/sdx1

+

# e2label /dev/sd'''x1''' USB_STICK

−

# e2label /dev/sdx1 USB_STICK</nowiki>}}

* For FAT32, install the {{Pkg|dosfstools}} package and run:

* For FAT32, install the {{Pkg|dosfstools}} package and run:

−

: {{bc|<nowiki>

+

# cfdisk /dev/sd'''x'''

−

# cfdisk /dev/sdx

+

# mkfs.vfat -F32 /dev/sd'''x1'''

−

# mkfs.vfat -F32 /dev/sdx1

+

# dosfslabel /dev/sd'''x1''' USB_STICK

−

# dosfslabel /dev/sdx1 USB_STICK</nowiki>}}

=== Without overwriting the USB drive ===

=== Without overwriting the USB drive ===

−

+

{{Out of date|This section may need an update. See the discussion.|Talk:USB_Flash_Installation_Media#About_making_the_installation_media_without_overwriting}}

This method is slightly more complicated than writing the image directly with {{ic|dd}}, but it does keep the drive usable for data storage. Before you begin, make sure that your USB device is formatted as either FAT32, EXT2/3/4 or Btrfs. For [[UEFI]] boot and/or interoperability with other operating systems you should use FAT32. Also, make sure that you have the ''syslinux'' package (version 4.04 or newer) installed.

This method is slightly more complicated than writing the image directly with {{ic|dd}}, but it does keep the drive usable for data storage. Before you begin, make sure that your USB device is formatted as either FAT32, EXT2/3/4 or Btrfs. For [[UEFI]] boot and/or interoperability with other operating systems you should use FAT32. Also, make sure that you have the ''syslinux'' package (version 4.04 or newer) installed.

Line 69:

Line 66:

{{Warning|Be very careful where you point {{ic|dd}} and please use the drive '''itself''' in the following commands, '''not''' the first partition. This is a very common mistake.}}

{{Warning|Be very careful where you point {{ic|dd}} and please use the drive '''itself''' in the following commands, '''not''' the first partition. This is a very common mistake.}}

−

{{Note|On some distributions the {{ic|mbr.bin}} file may be available as {{ic|/usr/'''share'''/syslinux/mbr.bin}}.}}

+

{{Note|On some distributions {{ic|mbr.bin}} may be available as {{ic|/usr/'''share'''/syslinux/mbr.bin}}.}}

−

$ cd /media/''somefolder''/arch/boot/syslinux #Where ''somefolder'' is the USB drive's mount point. Do not skip this step.

{{Note|While you ''could'' label the drive "{{ic|ARCH_2013XX}}" (with the appropriate release month), perhaps an even better approach is to use the [[UUID]] ''(this way you can re-label it whatever you want later without having to worry about it, or you could just leave it blank)''. Failing to do either '''will''' get you the famous '''30 seconds error'''.}}

+

{{Warning|Failure to label the drive "{{ic|ARCH_2013XX}}" (with the appropriate release month) or to use an [[UUID]] (to re-label it to whatever you like) '''will''' get you the infamous "30 seconds" error.}}

Here's how you can replace the {{ic|1=archisolabel=ARCH_2013XX}} part with your equivalent of {{ic|1=archiso'''device'''=/dev/disk/by-uuid/47FA-4071}} for both config files at the same time, using a single command:

Here's how you can replace the {{ic|1=archisolabel=ARCH_2013XX}} part with your equivalent of {{ic|1=archiso'''device'''=/dev/disk/by-uuid/47FA-4071}} for both config files at the same time, using a single command:

If the ''syslinux'' package on your distribution is older than version 4.06, as a workaround for FAT32 filesystems (unnecessary for EXT4), the {{ic|APPEND}} line from {{ic|syslinux.cfg}} should also be replaced:

If the ''syslinux'' package on your distribution is older than version 4.06, as a workaround for FAT32 filesystems (unnecessary for EXT4), the {{ic|APPEND}} line from {{ic|syslinux.cfg}} should also be replaced:

Line 91:

Line 88:

====Using UNetbootin====

====Using UNetbootin====

−

You can use UNetbootin on any Linux distribution or Windows to burn your iso on a USB key. What you need is to edit the file {{ic|syslinux.cfg}} to boot the correct kernel image after UNetbootin have burned the image. After burning open the USB key and edit {{ic|syslinu.cfg}}

+

UNetbootin can be used on any Linux distribution or Windows to copy your iso to a USB device. However, Unetbootin overwrites syslinux.cfg, so it creates a USB device that does not boot properly. For this reason, '''Unetbootin is not recommended''' -- please use {{ic|dd}} or one of the other methods discussed in this topic.

+

{{Warning|UNetbootin writes over the default {{ic|syslinux.cfg}}; this must be restored before the USB device will boot properly.}}

In {{ic|/dev/sdX1}} you must replace X with the first free letter after last is in use in the system where you would install Arch Linux ''(for example if you have 2 harddisk in your PC, you must replace X with the letter 'c'.)''. Is possible to make this change during the first phase of boot pressing {{ic|Tab}} when the menu will be showed.

+

In {{ic|/dev/sd'''x1'''}} you must replace '''x''' with the first free letter after the last letter in use on the system where you are installing Arch Linux (e.g. if you have two hard drives, use {{ic|c}}.). You can make this change during the first phase of boot by pressing {{ic|Tab}} when the menu is shown.

== On Mac OS X ==

== On Mac OS X ==

−

To be able to use dd on your usb device on a Mac you have to do some special maneuvers. First of all insert your usb device, OS X will automount it, and run

+

To be able to use {{ic|dd}} on your USB device on a Mac you have to do some special maneuvers. First of all insert your usb device, OS X will automount it, and in {{ic|Terminal.app}} run:

−

diskutil list

+

$ diskutil list

−

in Terminal.app. Figure out what your usb device is called - mine was called /dev/disk1. (Just use the `mount` command or `sudo dmesg | tail`.) Now you run

+

Figure out what your USB device is called with {{ic|mount}} or {{ic|<nowiki>sudo dmesg | tail</nowiki>}} (e.g. {{ic|/dev/disk1}}) and unmount the partitions on the device (i.e., /dev/disk1s1) while keeping the device proper (i.e., /dev/disk1):

−

diskutil unmountDisk /dev/disk1

+

$ diskutil unmountDisk /dev/disk1

−

to unmount the partitions on the device (i.e., /dev/disk1s1) while keeping the device proper (i.e., /dev/disk1). Now we can continue in accordance with the Linux instructions above (but use bs=8192 if you are using the OS X dd, the number comes from 1024*8).

+

Now we can continue in accordance with the instructions above (but use {{ic|1=bs=8192}} if you are using the OS X {{ic|dd}}, the number comes from {{ic|1024*8}}).

−

dd if=image.iso of=/dev/disk1 bs=8192

+

{{hc|<nowiki>dd if=image.iso of=/dev/disk1 bs=8192</nowiki>|

−

20480+0 records in

+

20480+0 records in

−

20480+0 records out

+

20480+0 records out

−

167772160 bytes transferred in 220.016918 secs (762542 bytes/sec)

+

167772160 bytes transferred in 220.016918 secs (762542 bytes/sec)

+

}}

−

it is probably a good idea to eject your drive before physical removal at this point.

+

It is probably a good idea to eject your drive before physical removal at this point:

−

diskutil eject /dev/disk1

+

$ diskutil eject /dev/disk1

== On Windows ==

== On Windows ==

−

=== Image Writer for Windows ===

+

=== Win32 Disk Imager ===

+

{{Warning|This will destroy all information on your USB flash drive!}}

+

First, download the program from [http://sourceforge.net/projects/win32diskimager/ here]. Next, extract the archive and run the executable. Now, select the Arch Linux ISO under the {{ic|Image File}} section and the USB flash device letter (for example, [D:\]) under the {{ic|Device}} section. Finally, click {{ic|Write}} when ready.

+

{{Tip|By default, the Win32 Disk Imager's file-browser assumes disk image files end with a {{ic|.img}} extension. However, you can simply change the {{ic|Files of type}} drop-down list to {{ic|*.*}} and continue on to selecting your Arch Linux ISO.}}

+

{{Note|After installation, you may need to restore the USB flash drive following a process as outlined [[USB_Installation_Media#How_to_restore_the_USB_drive|here]].}}

−

Download the program from http://sourceforge.net/projects/win32diskimager/ and run it. Select the arch image-file and usb stick. The Win32 Disk Imager's file browser assumes image files end with .img, so if the image-file you have selected ends with .iso, you will have to type its name in manually; this difference in suffixes is simply cosmetic however, the image will be written fine regardless. Click on the write button. Now you should be able to boot from the usb stick and install Arch Linux from it.

+

=== USBWriter for Windows ===

+

+

Download the program from http://sourceforge.net/projects/usbwriter/ and run it. Select the arch image file, the target USB stick, and click on the {{ic|write}} button. Now you should be able to boot from the usb stick and install Arch Linux from it.

From a command prompt, invoke flashnul with -p, and determine which device index is your USB drive. For example, my output looks like this:

+

From a command prompt, invoke flashnul with {{ic|-p}}, and determine which device index is your USB drive, e.g.:

−

−

C:\>flashnul -p

−

−

Avaible physical drives:

−

Avaible logical disks:

−

C:\

−

D:\

−

E:\

−

In my case, it is drive E:

+

{{hc|C:\>flashnul -p|

+

Avaible physical drives:

+

Avaible logical disks:

+

C:\

+

D:\

+

E:\

+

}}

−

When you have determined which device is the correct one, you can write the image to your drive, by invoking flashnul with the device index, -L, and the path to your image. In my case, it would be

+

When you have determined which device is the correct one, you can write the image to your drive, by invoking flashnul with the device index, {{ic|-L}}, and the path to your image, e.g:

−

C:\>flashnul E: -L path\to\arch.iso

+

C:\>flashnul '''E:''' -L ''path\to\arch.iso''

As long as you are really sure you want to write the data, type yes, then wait a bit for it to write. If you get an access denied error, close any Explorer windows you have open.

As long as you are really sure you want to write the data, type yes, then wait a bit for it to write. If you get an access denied error, close any Explorer windows you have open.

Line 163:

Line 168:

If under Vista or Win7, you should open the console as administrator, or else flashnul will fail to open the stick as a block device and will only be able to write via the drive handle windows provides

If under Vista or Win7, you should open the console as administrator, or else flashnul will fail to open the stick as a block device and will only be able to write via the drive handle windows provides

−

{{Note|Confirmed that you need to use drive letter as opposed to number. flashnul 1rc1, Windows 7 x64. -bgalakazam}}

+

{{Note|Confirmed that you need to use drive letter as opposed to number. flashnul 1rc1, Windows 7 x64.}}

=== The Cygwin Way ===

=== The Cygwin Way ===

−

Make sure your [http://www.cygwin.com/ Cygwin] installation contains the dd package. Or if you do not want to install Cygwin, you can simply download dd for windows from http://www.chrysocome.net/dd.

{{Tip|If you do not want to install Cygwin, you can download {{ic|dd}} for Windows from [http://www.chrysocome.net/dd here]. See the next section for more information.}}

−

Place your image file in your home directory, in my case it is:

+

Place your image file in your home directory:

C:\cygwin\home\John\

C:\cygwin\home\John\

Line 175:

Line 182:

Run cygwin as administrator (required for cygwin to access hardware). To write to your USB drive use the following command:

Run cygwin as administrator (required for cygwin to access hardware). To write to your USB drive use the following command:

−

dd if=image.iso of=\\.\[x]:

+

dd if=image.iso of=\\.\[x]: bs=4M

−

where image.iso is the path to the iso-image file within the cygwin directory and \\.\[x]: is your USB device where x is the windows designated letter, in my case "\\.\d:".

+

where image.iso is the path to the iso image file within the {{ic|cygwin}} directory and {{ic|\\.\['''x''']}}: is your USB flash drive where '''x''' is the windows designated letter, e.g. {{ic|\\.\d:}}.

−

On cygwin 6.0 find out the correct partition with

+

On Cygwin 6.0 find out the correct partition with:

cat /proc/partitions

cat /proc/partitions

Line 185:

Line 192:

and write the ISO image with the information from the output. Example:

and write the ISO image with the information from the output. Example:

−

{{Warning|This will irrevocably delete all files on your USB stick, so make sure you do not have any important files on the stick before doing this.}}

+

{{Warning|This will irrevocably delete all files on your USB flash drive, so make sure you do not have any important files on the stick before doing this.}}

−

dd if=image.iso of=/dev/sdb

+

dd if=image.iso of=/dev/sdb bs=4M

=== dd for Windows ===

=== dd for Windows ===

−

A GPL licensed dd version for Windows is available at http://www.chrysocome.net/dd. The advantage of this over Cygwin is smaller download. Use it as shown in instructions for Cygwin above.

+

{{Note|Some users have an "isolinux.bin missing or corrupt" problem when booting the media with this method.}}

−

=== Boot the entire ISO from RAM ===

+

A GPL licensed dd version for Windows is available at http://www.chrysocome.net/dd. The advantage of this over Cygwin is a smaller download. Use it as shown in instructions for Cygwin above.

−

This method uses [[Syslinux]] and '''[http://www.syslinux.org/wiki/index.php/MEMDISK MEMDISK]''' to load the entire ISO image in RAM, so make sure you have enough RAM to hold it. Once it's done loading and you see the graphical menu you can simply remove the USB stick and maybe even use it on a different machine to start the process all over again. It also allows booting and installing Arch from (and to) the same USB stick.

+

To begin, download the latest version of dd for Windows. Once downloaded, extract the archive's contents into Downloads or elsewhere.

−

'''1.''' Format the USB stick as FAT32 and create the following folders:

If your Arch Linux ISO is elsewhere you may need to state the full path, for convenience you may wish to put the Arch Linux ISO into the same folder as the dd executable. The basic format of the command will look like this.

−

X:\Boot\ISOs

−

X:\Boot\Settings

−

'''2.''' Copy the ISO you'd like to boot to the "ISOs" folder (e.g. ''archlinux-2013.04.01-dual.iso''), and extract from the '''[http://www.kernel.org/pub/linux/utils/boot/syslinux/ latest release]''' (e.g. ''syslinux-4.05.zip''):

{{Warning|This command will replace the drive's contents and its formatting with the ISO's. You will likely be unable to recover its contents in the event of an accidental copy. Be absolutely sure that you are directing dd to the correct drive before executing!}}

+

Simply replace the various null spots (indicated by an "x") with the correct date and correct drive letter.

This method uses [[Syslinux]] and a [[Ramdisk]] ([http://www.syslinux.org/wiki/index.php/MEMDISK MEMDISK]) to load the entire Arch Linux ISO image into RAM. Since this will be running entirely from system memory, you will need to make sure the system you will be installing this on has an adequate amount. A minimum amount of RAM between 500 MB and 1 GB should suffice for a MEMDISK based, Arch Linux install.

−

And while you're in this folder, create a {{ic|syslinux.cfg}} file:

+

For more information on Arch Linux system requirements as well as those for MEMDISK see the [[Beginners' Guide]] and [http://www.etherboot.org/wiki/bootingmemdisk#preliminaries here].

−

+

{{Tip|Once the installer has completed loading you can simply remove the USB stick and even use it on a different machine to start the process all over again. Utilizing MEMDISK also allows booting and installing Arch Linux to and from the same USB flash drive.}}

−

{{hc|X:\Boot\Settings\syslinux.cfg|2=

+

====Preparing the USB flash drive====

+

Begin by formatting the USB flash drive as '''FAT32'''. Then create the following folders on the newly formatted drive.

+

* {{ic|Boot}}

+

** {{ic|Boot/ISOs}}

+

** {{ic|Boot/Settings}}

+

====Copy the needed files to the USB flash drive====

+

Next copy the ISO that you would like to boot to the {{ic|Boot/ISOs}} folder. After that, extract from the following files from the latest release of {{pkg|syslinux}} from [http://www.kernel.org/pub/linux/utils/boot/syslinux/ here] and copy them into the following folders.

+

* {{ic|./win32/syslinux.exe}} to the Desktop or Downloads folder on your system.

After copying the needed files, navigate to the USB flash drive, /boot/Settings and create a {{ic|syslinux.cfg}} file.

+

{{Warning|On the {{ic|INITRD}} line, be sure to use the name of the ISO file that you copied to your {{ic|ISOs}} folder!}}

+

{{hc|/Boot/Settings/syslinux.cfg|2=

DEFAULT arch_iso

DEFAULT arch_iso

Line 217:

Line 238:

MENU LABEL Arch Setup

MENU LABEL Arch Setup

LINUX memdisk

LINUX memdisk

−

INITRD /Boot/ISOs/archlinux-2013.04.01-dual.iso

+

INITRD /Boot/ISOs/archlinux-2013.08.01-dual.iso

APPEND iso}}

APPEND iso}}

−

+

For more information on Syslinux see the [[Syslinux|Arch Wiki article]].

−

{{Tip|If you want to add more distributions ''(Debian and Parted Magic were tested)'' you can edit this file. Maybe even give it a nice menu and a background image, instead of defaulting to the Arch Linux ISO. Refer to the [[Syslinux]] wiki.}}

+

====Final steps====

−

+

Finally, create a {{ic|*.bat}} file where {{ic|syslinux.exe}} is located and run it ("Run as administrator" if you're on Vista or Windows 7):

−

'''3.''' Finally, create a {{ic|*.bat}} file where {{ic|syslinux.exe}} is located and run it ("Run as administrator" if you're on Vista or Windows 7):

−

{{hc|C:\Documents and Settings\username\Desktop\install.bat|

{{hc|C:\Documents and Settings\username\Desktop\install.bat|

@echo off

@echo off

syslinux.exe -m -a -d /Boot/Settings X:}}

syslinux.exe -m -a -d /Boot/Settings X:}}

−

Done.

+

=== Add to a MULTIBOOT Live USB ===

+

+

The Windows tool [http://www.pendrivelinux.com/yumi-multiboot-usb-creator/ YUMI MultiBoot Live USB Creator] can be used to quickly create a Live USB media with multiple Installers of many Linux distros. Once created, Installers can be added or removed without reformatting the USB drive.

== Troubleshooting ==

== Troubleshooting ==

−

{{Note| For the MEMDISK Method, if you get the famous '''30 seconds error''' trying to boot the i686 version, press the {{Keypress|Tab}} key over the {{ic|Boot Arch Linux (i686)}} entry and add {{ic|vmalloc&#61;448M}} at the end. This only applies to the MEMDISK method. For reference: ''If your image is bigger than 128MiB and you have a 32-bit OS, then you have to increase the maximum memory usage of vmalloc''. [http://www.syslinux.org/wiki/index.php/MEMDISK#-_memdiskfind_in_combination_with_phram_and_mtdblock (*)]}}

+

{{Note|For the [[#Boot the entire ISO from RAM|MEMDISK Method]], if you get the famous "30 seconds" error trying to boot the i686 version, press the {{Keypress|Tab}} key over the {{ic|Boot Arch Linux (i686)}} entry and add {{ic|vmalloc&#61;448M}} at the end. For reference: ''If your image is bigger than 128MiB and you have a 32-bit OS, then you have to increase the maximum memory usage of vmalloc''. [http://www.syslinux.org/wiki/index.php/MEMDISK#-_memdiskfind_in_combination_with_phram_and_mtdblock (*)]}}

−

{{Note|In general, if you get the '''30 seconds error''' due to the /dev/disk/by-label/ARCH_XXXXXX not mounting, try renaming your USB media to ARCH_XXXXXX, for example ARCH_201302, and try to boot the media once again. It should fix the error.}}

+

{{Note|If you get the "30 seconds" error due to the {{ic|/dev/disk/by-label/ARCH_XXXXXX}} not mounting, try renaming your USB media to {{ic|ARCH_XXXXXX}} (e.g. {{ic|ARCH_201302}}).}}

This page discusses various methods on how to write an Arch Linux release to a USB drive (also referred to as "flash drive", "USB stick", "USB key", etc). The result will be a LiveCD-like system ("LiveUSB", if you will) that, because of the nature of SquashFS, will discard all changes once the computer shuts down.

On GNU/Linux

Overwrite the USB drive

Tip: Check with lsblk that the USB device is not mounted (i.e. listed but has no mountpoint), and use /dev/sdx instead of /dev/sdx1.
These are very common mistakes!

# dd bs=4M if=/path/to/archlinux.iso of=/dev/sdx && sync

How to restore the USB drive

Because the ISO image is a hybrid which can either be burned to a disc or directly written to a USB drive, it doesn't include a standard partition table.

After you install Arch Linux and you're done with the USB drive, you should zero out its first 512 bytes (meaning the boot code from the MBR and the non-standard partition table) if you want to restore it to full capacity:

# dd count=1 bs=512 if=/dev/zero of=/dev/sdx && sync

Then create a new partition table (e.g. "msdos") and filesystem (e.g. EXT4, FAT32) using gparted, or from a terminal:

This method is slightly more complicated than writing the image directly with dd, but it does keep the drive usable for data storage. Before you begin, make sure that your USB device is formatted as either FAT32, EXT2/3/4 or Btrfs. For UEFI boot and/or interoperability with other operating systems you should use FAT32. Also, make sure that you have the syslinux package (version 4.04 or newer) installed.

1. Extract the arch folder from the ISO to the USB drive. For UEFI motherboards follow these instructions.

2. Install the Syslinux bootloader:

Warning: Be very careful where you point dd and please use the drive itself in the following commands, not the first partition. This is a very common mistake.

Note: On some distributions mbr.bin may be available as /usr/share/syslinux/mbr.bin.

If the syslinux package on your distribution is older than version 4.06, as a workaround for FAT32 filesystems (unnecessary for EXT4), the APPEND line from syslinux.cfg should also be replaced:

$ sed -i "s|../../|/arch|" syslinux.cfg

Using UNetbootin

UNetbootin can be used on any Linux distribution or Windows to copy your iso to a USB device. However, Unetbootin overwrites syslinux.cfg, so it creates a USB device that does not boot properly. For this reason, Unetbootin is not recommended -- please use dd or one of the other methods discussed in this topic.

Warning: UNetbootin writes over the default syslinux.cfg; this must be restored before the USB device will boot properly.

In /dev/sdx1 you must replace x with the first free letter after the last letter in use on the system where you are installing Arch Linux (e.g. if you have two hard drives, use c.). You can make this change during the first phase of boot by pressing Tab when the menu is shown.

On Mac OS X

To be able to use dd on your USB device on a Mac you have to do some special maneuvers. First of all insert your usb device, OS X will automount it, and in Terminal.app run:

$ diskutil list

Figure out what your USB device is called with mount or sudo dmesg | tail (e.g. /dev/disk1) and unmount the partitions on the device (i.e., /dev/disk1s1) while keeping the device proper (i.e., /dev/disk1):

$ diskutil unmountDisk /dev/disk1

Now we can continue in accordance with the instructions above (but use bs=8192 if you are using the OS X dd, the number comes from 1024*8).

It is probably a good idea to eject your drive before physical removal at this point:

$ diskutil eject /dev/disk1

On Windows

Win32 Disk Imager

Warning: This will destroy all information on your USB flash drive!

First, download the program from here. Next, extract the archive and run the executable. Now, select the Arch Linux ISO under the Image File section and the USB flash device letter (for example, [D:\]) under the Device section. Finally, click Write when ready.

Tip: By default, the Win32 Disk Imager's file-browser assumes disk image files end with a .img extension. However, you can simply change the Files of type drop-down list to *.* and continue on to selecting your Arch Linux ISO.

Note: After installation, you may need to restore the USB flash drive following a process as outlined here.

USBWriter for Windows

Download the program from http://sourceforge.net/projects/usbwriter/ and run it. Select the arch image file, the target USB stick, and click on the write button. Now you should be able to boot from the usb stick and install Arch Linux from it.

The Flashnul Way

From a command prompt, invoke flashnul with -p, and determine which device index is your USB drive, e.g.:

C:\>flashnul -p

Avaible physical drives:
Avaible logical disks:
C:\
D:\
E:\

When you have determined which device is the correct one, you can write the image to your drive, by invoking flashnul with the device index, -L, and the path to your image, e.g:

C:\>flashnul E: -L path\to\arch.iso

As long as you are really sure you want to write the data, type yes, then wait a bit for it to write. If you get an access denied error, close any Explorer windows you have open.

If under Vista or Win7, you should open the console as administrator, or else flashnul will fail to open the stick as a block device and will only be able to write via the drive handle windows provides

Note: Confirmed that you need to use drive letter as opposed to number. flashnul 1rc1, Windows 7 x64.

If your Arch Linux ISO is elsewhere you may need to state the full path, for convenience you may wish to put the Arch Linux ISO into the same folder as the dd executable. The basic format of the command will look like this.

dd if=archlinux-2013-XX-xx-dual.iso of=\\.\x: bs=4m

Warning: This command will replace the drive's contents and its formatting with the ISO's. You will likely be unable to recover its contents in the event of an accidental copy. Be absolutely sure that you are directing dd to the correct drive before executing!

Simply replace the various null spots (indicated by an "x") with the correct date and correct drive letter.

Here is a complete example.

dd if=ISOs\archlinux-2013.08.01-dual.iso of=\\.\d: bs=4M

Loading the installation media from RAM

This method uses Syslinux and a Ramdisk (MEMDISK) to load the entire Arch Linux ISO image into RAM. Since this will be running entirely from system memory, you will need to make sure the system you will be installing this on has an adequate amount. A minimum amount of RAM between 500 MB and 1 GB should suffice for a MEMDISK based, Arch Linux install.

For more information on Arch Linux system requirements as well as those for MEMDISK see the Beginners' Guide and here.

Tip: Once the installer has completed loading you can simply remove the USB stick and even use it on a different machine to start the process all over again. Utilizing MEMDISK also allows booting and installing Arch Linux to and from the same USB flash drive.

Preparing the USB flash drive

Begin by formatting the USB flash drive as FAT32. Then create the following folders on the newly formatted drive.

Boot

Boot/ISOs

Boot/Settings

Copy the needed files to the USB flash drive

Next copy the ISO that you would like to boot to the Boot/ISOs folder. After that, extract from the following files from the latest release of syslinux from here and copy them into the following folders.

./win32/syslinux.exe to the Desktop or Downloads folder on your system.

./memdisk/memdisk to the Settings folder on your USB flash drive.

Create the configuration file

After copying the needed files, navigate to the USB flash drive, /boot/Settings and create a syslinux.cfg file.

Warning: On the INITRD line, be sure to use the name of the ISO file that you copied to your ISOs folder!

Final steps

Finally, create a *.bat file where syslinux.exe is located and run it ("Run as administrator" if you're on Vista or Windows 7):

C:\Documents and Settings\username\Desktop\install.bat

@echo off
syslinux.exe -m -a -d /Boot/Settings X:

Add to a MULTIBOOT Live USB

The Windows tool YUMI MultiBoot Live USB Creator can be used to quickly create a Live USB media with multiple Installers of many Linux distros. Once created, Installers can be added or removed without reformatting the USB drive.

Troubleshooting

Note: For the MEMDISK Method, if you get the famous "30 seconds" error trying to boot the i686 version, press the Template:Keypress key over the Boot Arch Linux (i686) entry and add vmalloc=448M at the end. For reference: If your image is bigger than 128MiB and you have a 32-bit OS, then you have to increase the maximum memory usage of vmalloc. (*)

Note: If you get the "30 seconds" error due to the /dev/disk/by-label/ARCH_XXXXXX not mounting, try renaming your USB media to ARCH_XXXXXX (e.g. ARCH_201302).